The atomic level mechanism of white phosphorous demolition by di-iodine

Mealli, Carlo and Ienco, Andrea and Peruzzini, Maurizio and Manca, Gabriele (2018) The atomic level mechanism of white phosphorous demolition by di-iodine. Dalton Transactions, 47 (2). pp. 394-408. ISSN 1477-9226

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Abstract

A detailed mechanism of the I2-induced transformation of white phosphorus into PI3 emerges from a DFT analysis. The multi-step process implies at any stage one P P and two I I bond cleavages, associated to the formation of two P I bonds plus an in situ generated brand new I2 molecule. Significant electron transfer between atoms is observed at any step, but the reactions better define as concerted rather than redox. Along the steepest descent to the product, no significant barrier is encountered except for the very first P4 activation, which costs +14.6 kcal mol-1. At the atomic level, one first I2 molecule, a typical mild oxidant, is first involved in a linear halogen bonding interaction (XB) with one P donor, while its terminal I atom is engaged in an additional XB adduct with a second I2. Significant electron transfer through the combined diatomics allows the external I atom of the dangling I3 grouping to convey electrons into the * level of one P P bond with its consequent cleavage. This implies at some point the appearance of a six-membered ring, which alternative switches its bonding and no-bonding interactions. The final transformation of the P2I4 diphosphine into two PI3 phosphines is enlightening also for the specific role of the I substituents. In fact, it is proved that an organo-diphosphine analogue hardly undergoes the separation of two phosphines, as reported in literature. This is attributable to the particularly high donor power of the carbo-substituted P atoms, which prevents the concertedness of the reaction but favors charge separation in an unreactive ion pair.

Item Type:	Article
Subjects:	500 Scienze naturali e Matematica > 540 Chimica e scienze connesse
Depositing User:	Dr. Andrea Ienco
Date Deposited:	27 Jun 2018 10:57
Last Modified:	27 Jun 2018 11:25
URI:	http://eprints.bice.rm.cnr.it/id/eprint/17919

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